Field of the Invention
The present invention relates to mobile communication.
Related Art
The 3rd generation partnership project (3GPP) long term evolution (LTE) evolved from a universal mobile telecommunications system (UMTS) is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) evolved from the 3GPP LTE.
As disclosed in 3GPP TS 36.211 V10.4.0 (2011-12) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 10)”, 3GPP LTE/LTE-A may divide the physical channel into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
Meanwhile, Power Headroom (PH) information of a terminal can be used to form a method for a base station to utilize resources of a terminal efficiently. Power control technology (or power adjustment technology) is an essential element for minimizing interference and reduce battery consumption of a terminal to achieve efficient distribution of resources in wireless communication. If a terminal provides PH information to a base station, the base station can estimate uplink maximum transmission power that a terminal can tolerate. Then the base station can provide uplink scheduling such as Transmit Power Control (TPC), Modulation and Coding Scheme (MCS), and bandwidth to the terminal within the estimated uplink maximum transmission power.
Also, a situation in which cells or cell groups at different geographic locations exchange signals or channels related to control and/or data can be taken into account in the next version of the system.
At this time, scheduling information among cells or cell groups at different geographic locations may not be shared dynamically but can be performed independently; in this case, transmission of each Uplink Control Information (UCI) to the corresponding dedicated cell can be taken into account.
In other words, transmitting UCI about a first base station (eNodeB1) to the first base station and transmitting UCI about a second base station (eNodeB2) to the second base station can be taken into account.
In this case, it can be described that duel connectivity has been established for a terminal connected to both of the first and the second base station.
However, in the case of dual connectivity, how a terminal transmits Power Headroom Reporting (PHR) to the first or the second base station is still left unsolved.